Shallow trench isolation forming method and structures resulting therefrom

Abstract

A method includes forming a first plurality of fins in a first region of a substrate, a first recess being interposed between adjacent fins in the first region of the substrate, the first recess having a first depth and a first width, forming a second plurality of fins in a second region of the substrate, a second recess being interposed between adjacent fins in the second region of the substrate, the second recess having a second depth and a second width, the second width of the second recess being less than the first width of the first recess, the second depth of the second recess being less than the first depth of the first recess, forming a first dielectric layer in the first recess and the second recess, and converting the first dielectric layer in the first recess and the second recess to a treated dielectric layer.

What is claimed is: 
     
       1. A method of forming a semiconductor device, the method comprising:
 etching a first trench in a first region of a semiconductor substrate to form a first fin and a second fin that are disposed on opposites sides of the first trench, wherein the first trench has a first depth and a first width; 
 etching a second trench in a second region of the semiconductor substrate to form a third fin and a fourth fin that are disposed on opposites sides of the second trench, wherein the second trench has a second depth that is smaller than the first depth, and wherein the second trench has a second width that is smaller than the first width; 
 depositing a first dielectric material over the first fin, the second fin, the third fin and the fourth fin to form a first dielectric layer that fills the first trench and the second trench; and 
 converting an entire thickness of the first dielectric layer in the first trench and an entire thickness of the first dielectric layer in the second trench to a second dielectric material wherein a concentration of nitrogen in the second dielectric material in the second trench is within 10 percent of a concentration of nitrogen in the second dielectric material in the first trench. 
 
     
     
       2. The method of  claim 1 , wherein while converting the entire thickness of the first dielectric layer in the first trench and the entire thickness of the first dielectric layer in the second trench, a first rate of conversion of the first dielectric layer in the first trench is higher than a second rate of conversion of the first dielectric layer in the second trench. 
     
     
       3. The method of  claim 2 , wherein the first rate of conversion of the first dielectric layer in the first trench is in a range from 7.75 nm/(min) 1/2  to 700 nm/(min) 1/2 , and wherein the second rate of conversion of the first dielectric layer in the second trench is in a range from 6.2 nm/(min) 1/2  to 600 nm/(min) 1/2 . 
     
     
       4. The method of  claim 1 , wherein the first depth is in a range from 100 nm to 180 nm and the second depth is in a range from 40 nm to 170 nm. 
     
     
       5. The method of  claim 1 , wherein a difference in height between a first fin height of the first fin and a second fin height of the third fin is in a range from 10 nm to  6   o  nm. 
     
     
       6. The method of  claim 1 , wherein converting the entire thickness of the first dielectric layer in the first trench and the entire thickness of the first dielectric layer in the second trench comprises annealing the first dielectric layer in an oxygen-containing ambient. 
     
     
       7. The method of  claim 1 , wherein converting the entire thickness of the first dielectric layer in the first trench and the entire thickness of the first dielectric layer in the second trench comprises a thermal anneal process performed at a temperature in a range from 300° C. to 700° C. 
     
     
       8. The method of  claim 1 , further comprising recessing the first dielectric layer, wherein after recessing the first dielectric layer, a top surface of the first dielectric layer is level with a bottom surface of the second trench. 
     
     
       9. A method of forming a semiconductor device, the method comprising:
 patterning a first region of a semiconductor substrate to form a first plurality of fins in the first region; 
 patterning a second region of the semiconductor substrate to form a second plurality of fins in the second region, wherein a first width between adjacent fins of the first plurality of fins is larger than a second width between adjacent fins of the second plurality of fins; 
 depositing a first dielectric material over the first plurality of fins and the second plurality of fins, wherein the first dielectric material spans the first width between the adjacent fins of the first plurality of fins and spans the second width between the adjacent fins of the second plurality of fins; 
 converting the first dielectric material to a second dielectric material, wherein a first rate of conversion of the first dielectric material between the adjacent fins of the first plurality of fins is higher than a second rate of conversion of the first dielectric material between the adjacent fins of the second plurality of fins. 
 
     
     
       10. The method of  claim 9 , wherein the second dielectric material comprises an oxide. 
     
     
       11. The method of  claim 9 , wherein at a first point of time during converting the first dielectric material, a first thickness of the first dielectric material between the adjacent fins of the first plurality of fins is converted to the second dielectric material and a second thickness of the first dielectric material between the adjacent fins of the second plurality of fins is converted to the second dielectric material, the first thickness being larger than the second thickness. 
     
     
       12. The method of  claim 11 , wherein at a second point of time after the first point of time the first dielectric material between the adjacent fins of the first plurality of fins and the first dielectric material between the adjacent fins of the second plurality of fins is fully converted to the second dielectric material. 
     
     
       13. The method of  claim 12 , wherein at the second point of time a nitrogen concentration of the second dielectric material between the adjacent fins of the first plurality of fins and the second dielectric material between the adjacent fins of the second plurality of fins is in a range from 1×10 19  atoms/cm 3  to 1×10 21  atoms/cm 3 . 
     
     
       14. The method of  claim 9 , wherein a first ratio of a first height of the first plurality of fins to the first width is larger than a second ratio of a second height of the second plurality of fins to the second width. 
     
     
       15. A method of forming a semiconductor device, the method comprising:
 forming a first plurality of fins in a first region of a substrate, wherein the first plurality of fins have a first fin density; 
 forming a second plurality of fins in a second region of the substrate, wherein the second plurality of fins have a second fin density that is greater than the first fin density; 
 filling a first recess between adjacent fins of the first plurality of fins with a first dielectric material; 
 filling a second recess between adjacent fins of the second plurality of fins with the first dielectric material; and 
 converting the first dielectric material in the first recess and the second recess to a second dielectric material, wherein during converting the first dielectric material, a first conversion rate of the first dielectric material in the first recess is greater than a second conversion rate of the first dielectric material in the second recess. 
 
     
     
       16. The method of  claim 15 , wherein the second dielectric material comprises an oxide. 
     
     
       17. The method of  claim 15 , wherein a bottom surface of the second recess is higher than a bottom surface of the first recess. 
     
     
       18. The method of  claim 17 , further comprising performing an etching process to remove the second dielectric material from the second recess, wherein after performing the etching process, the bottom surface of the second recess is exposed. 
     
     
       19. The method of  claim 15 , wherein the second dielectric material has a nitrogen concentration in a range from 1×10 19  atoms/cm 3  to 1×10 21  atoms/cm 3 . 
     
     
       20. The method of  claim 15 , wherein converting the first dielectric material in the first recess and the second recess to the second dielectric material comprises a thermal anneal process performed at a temperature in a range from 300° C. to 700° C., and at a pressure in a range from 400 Torr to about 760 Torr.